Customized mobile terminal sales gradually become a trend, for example, in order to obtain more wireless network users, operators often launch a marketing strategy that customers can get mobile phones for free if they pay the mobile phone bills, in which case, in order to ensure that customers use the operators' own networks, operators require to add a network locking function to their customized mobile phones such that customers can only use the operators' own networks.
Mobile phones with a network locking function can only use a specific operator's Subscriber Identity Module (SIM) card. When the mobile phone detects that the Mobile Country Code (MCC) and Mobile Network Code (MNC) of a SIM card inserted into the mobile phone are inconsistent with the preset parameters within the mobile phone, it does not allow the mobile phone to search for the corresponding service network. The network locking of the mobile phone brings along the benefits of retaining customers for the operators, but in some countries or in some cases, the network must be unlocked for a network locked mobile phone. For example: some countries do not allow network locking, or restricts that the mobile phone can only be network locked for a certain period of time.
Currently, there lacks alternative methods for network unlocking. The user needs to hand the mobile phone to service personnel of the mobile phone manufacturer, and the service personnel uses a special unlocking software tool to unlock the network, whose implementation is relatively cumbersome.
For example, in the application “method and system for unlocking locked network of terminal” (Application No.: CN200910188960), by interconnecting the SIM TOOL KIT (STK) module of the SIM card with the operator's remote server, the remote server can poll the unlocking time in real time, and sends an AT command for unlocking to the mobile phone which meets the unlocking time, so as to unlock the mobile phone. The disadvantage of the application is that the authentication of the unlocking time is relatively complicated; since it requires that the STK module of the SIM card support the network unlocking service, when the SIM card is changed, the corresponding data on the remote server need to be updated. For another example, in an application for a method for encrypting and decrypting mobile terminal network locking/card locking unlock code” (CN200810110663), a method for encrypting and decrypting the unlocking code with asymmetric keys is disclosed, but the problem about how the mobile terminal acquires the unlocking code and unlocks the network is not involved.